| Summary: | 碩士 === 國立中興大學 === 植物病理學系所 === 104 === Ambrosia beetles are members of Platypodinae and Scolytinae (Coleoptera：Curculionidae). They usually excavate the tunnels (gallery) in the xylem of dying or recently dead trees. The symbiotic fungi which are the only nutrient source for larvae and the adults are released from the mycangium of ambrosia beetles to the gallery and then grow on it. Ambrosiella (Sodariomycetes, Microascales, Ceratocystidaceae) was reported to be the only fungal genus associated with ambrosia beetles with mesothoracic mycangium in the beetle tribe Xyleborini (Curculionidae, Scolytinae). There are five genera of beetles having mesothoracic type mycangium in the tribe Xyloborini, including Xylosandrus, Cnestus, Eccoptopterus, Hadrodemius and Anisandrus. These beetles were collected and their symbiotic fungi were isolated. It confirms that all fungi associated with beetles having mesothoracic mycangium belong to Ambrosiella. The identification was based on morphological features and phylogenetic analyses from genes of ITS rDNA, TEF1-α and RPB1. Four new records, Ambrosiella roeperi, Ambrosiella beaveri, Ambrosiella nakashimae and Ambrosiella grosmaniae and one new species, Ambrosiella catenulata sp. nov., were found. A fungus isolated from the Scolytoplatypodini (Scolytoplatypus pubescens) with pronotum mycangium belongs to a new proposed genus, Ambrosiopsis globosa. The separation between Ambrosiella and Ambrosiopsis is also supported by molecular analyses. Co-evolution between Ambrosiella species and their beetle symbionts are evaluated. The diverse Ambrosiella species and their relationship with native ambrosia beetles have progressively established in Taiwan.
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